A wide variety of processes use co-current flow reactors, or reactors where there is a single phase fluid that flows over a solid bed of particulate materials, to provide for contact between the fluid and a solid. In a reactor, the solid usually comprises a catalytic material on which the fluid reacts to form a product. The fluid can be a liquid, vapor, or mixture of liquid and vapor, and the fluid reacts to form a liquid, vapor, or a mixture of a liquid and vapor. The processes cover a range of processes, including hydrocarbon conversion, gas treatment, and adsorption for separation.
Co-current reactors with fixed beds are constructed such that the reactor allows for the fluid to flow over the reactor bed. When the fluid is a liquid, or liquid and vapor, the fluid is usually directed to flow downward through the reactor. There are many aspects for providing good contact between the fluid and the solid. Multiple bed, or multibed, reactors are also frequently used, where the reactor beds are stacked one over the other within a reactor shell. Typically, they are stacked with some space between the beds.
With multibed reactors the space between beds are convenient mixing zones. The between bed spaces are often used to provide for intermediate treatment of the process fluid, such as cooling the process fluid, heating the process fluid, or remixing and redistribution of the process fluid.
In exothermic catalytic reactions, the control of temperature is important, and the multibed system provides a convenient place for the injection of a quench gas. In hydrocarbon processing, the quench gas is often a cool hydrogen stream. However, cooling a fluid without controlling the mixing and distribution leads to uneven heating and reactions in subsequent reactor beds. And complex mixing and distribution systems takes up valuable space in a reactor chamber holding multiple reactor beds.
The design of reactors to overcome these limitations can save significantly on the valuable space within a reactor and to better utilize a reactor chamber. Hardware for holding a reactor, the reactor shell, is expensive, and takes significant time to design and construct before putting into operation. New reactor internals that improve the utilization of the space within a reactor shell can provide significant cost savings, and obviate the need for new reactor shell components, as well as prevent the down time for replacing an entire reactor.